The subject matter disclosed herein generally relates to components for combustors in gas turbine engines and, more particularly, to improved cooling for components of combustors of gas turbine engines.
Gas turbine engines, such as those that power modern commercial and military aircraft, include a compressor section to pressurize a supply of air, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases and generate thrust. The combustor section generally includes a plurality of circumferentially distributed fuel injectors that project toward a combustion chamber to supply fuel to be mixed and burned with the pressurized air. Gas turbine engines typically include a plurality of centralized staging valves in combination with one or more fuel supply manifolds that deliver fuel to the fuel injectors.
Each fuel injector typically has an inlet fitting connected to the manifold at the base, a conduit connected to the base fitting, and a nozzle connected to the conduit to spray the fuel into the combustion chamber. Appropriate valves or flow dividers are provided to direct and control the flow of fuel through the nozzle.
A combustor may include pilot and main fuel injectors. Generally, the main fuel injectors are for normal and high power situations, while the pilot fuel injectors are used for start operation or for emission control. The main or pilot fuel injectors have relatively small openings in the nozzles and small fuel passages in the conduits that may be prone to coke formation due to high fuel temperature. Coke formation may result in narrowed fuel openings in the nozzles, uneven fuel burn and increased maintenance requirements. Further, coke formation may form in the fuel conduit of the fuel injector, break off in fragments and ultimately obstruct fuel injector nozzle tip openings.
Conventional fuel injector designs typically utilize heat shields around the fuel injector conduit to provide a passive insulated, static, air gap and reduce the heat transfer rate within a diffuser case module to the fuel.